pay roll account kept under Zero Balance System . calculate pre tax

Slimware is considering establishing a zero-balance system for its payroll account. Currently, the firm pays its hourly employees every week on late Friday afternoon and puts a check for $750,000 in the bank to cover the payroll each Monday morning. Slimware has determined that the checks clear its bank as follows:

What is the annual pretax return to Slimware if the firm can earn 9% on any funds released from employing the zero-balance system? Assume the company has 52 weekly pay periods each year.